The present invention relates generally to arrowheads, and relates more specifically to arrowheads with pivotably mounted blades which fold against the body for flight and deploy only after contact with the target.
Arrowheads are known in which the blades are folded against the body while the arrow is in flight and then open on or after impact with the target. Having the blades folded against the body during flight increases the aerodynamic efficiency and accuracy of the arrowhead. Each blade is pivotably mounted to the arrowhead body at its rearward end. A beveled forward edge on each blade causes the blades to pivot rearward into an open position upon contact with the target, thereby extending the blades and increasing the cutting power of the arrowhead. The extent of the arc through which the blades travel determines the cut diameter of the arrowhead.
In a variation on this design, arrowheads suitable for bow fishing have their blades folded against the body during flight. These blades are pivotably mounted at their forward ends, however, and the blades remain folded against the body after contact with the target Once the arrow has penetrated through the body of the fish, if the struggling fish begins to work his way off the arrow, beveled surfaces at the rearward edges of the blades engage the fish and force the blades open, preventing the fish from sliding off the arrow.
Stated generally, the present invention comprises an arrowhead having a body with a mounting location adjacent a first end of the body. An elongated blade has a first end of the blade pivotably mounted to the mounting location of the body about an axis of rotation such that the blade is pivotably movable between first and second positions. The blade lies substantially parallel to the longitudinal axis of the body when in the first position with the second end of the blade adjacent the second end of the body, and the blade extending outward and toward or closer to the first end of the body when the blade is in the second position.
A bearing surface is formed at the second end of the blade so as to be contacted by a target surface to pivot the blade from the first position to the second position when the bearing surface strikes a target.
The blade has a cam portion formed thereon adjacent the axis of rotation. A spring adjacent the axis of rotation of the blade is oriented to exert a force against the cam portion of the blade in the approximate direction of the axis of rotation. The cam portion of the blade is configured such that a biasing force tending to pivot the blade into the first position is exerted only during a first minor portion of rotation of the blade between the first position and the second position.
In one preferred embodiment the mounting surface is adjacent the rearward end of the arrowhead body, and the bearing surfaces on the second ends of the blades face toward the forward end of the arrowhead body when the blades are in their first position. When the arrowhead strikes a target, the impact of the bearing surfaces with the target causes the blades to pivot and to deploy rearward.
In another preferred embodiment the mounting surface is adjacent the forward end of the arrowhead body, and the bearing surfaces on the second ends of the blades face rearward when the blades are in their first position. This arrowhead is suitable for bow fishing. When the arrow penetrates a fish, if the arrow tries to pull back through the fish, the blades will deploy substantially perpendicular to the longitudinal axis of the arrowhead body upon contact with the fish to prevent the arrowhead from passing back through the hole in the fish.
In one preferred embodiment, the axis of rotation is provided by an axle pin, and the spring adjacent the axis of rotation is provided by a spring pin substantially parallel to the axle pin. In still another preferred embodiment the axle pin and spring pin are joined at their upper ends to form a U-shaped unitary structure.
In another preferred embodiment the head of the blades is configured into a cam surface such that the spring pin bears against it only during predetermined portions of its rotation, thereby exerting a closing force during a first minor portion of rotation of the blades between their first and second positions.
Objects, features, and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the drawings and the appended claims.